Key drilling technologies for horizontal wells with long intervals,Sulige gasfield:An example from S77-35-H5 well
In order to further reduce drilling costs,improve single-well production and solve problems existing in the re-placing of"rotary steering + oil-based drilling fluid"with"conventional power tools + water-based drilling fluid"in hori-zontal wells with long intervals,several technologies were applied to such wells in Sulige gasfield to achieve the low-cost development.Results show that(ⅰ)the"dual two-dimension seven-interval"trajectory can deal with drilling tools'bending and some difficulties in setting screw tool face;(ⅱ)both mathematical modeling and engineering intervention can enhance the degree of hole cleaning with effect;(ⅲ)one technology integrating wellbore pressure monitoring with floating casing running can complete smooth running;(ⅳ)the technology of near-bit GR geosteering can boost the drilling rate in sand-body;and(ⅴ)the organic salt drilling-fluid system is able to guard against downhole collapse and lost circulation effective-ly.The application of these technologies makes the friction during the trip and the drilling torque individually reduced by 11％and 17％,and the composite rate of penetration increased by 28％.As a result,the drilling costs are cut down.In conclusion,this technological success provides a basis for the low-cost development of horizontal wells with long intervals in Sulige gasfield and creates novel ideas for improving both quality and efficiency in oil and gasfields.
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